Social Explorer; U.S. Census Bureau; Census of Population and Housing, 1980: Summary Tape File 3 [machine-readable data file] / conducted By the U.S. Bureau of the Census. Washington: Bureau of the Census [producer and distributor], 1982.

Census of Population and Housing, 1980: Summary Tape File 3 [machine-readable data file] / conducted by the U.S. Bureau of the Census. -Washington: Bureau of the Census [producer and distributor], 1982.

STF 1 provides 321 cells of complete-count population and housing data. Data are summarized for the United States, regions, divisions, States, SCSA's, SMSA's urbanized areas, congressional districts, counties, county subdivisions, places, census tracts, enumeration districts in unblocked areas, and blocks and block groups in blocked areas. This file set includes data shown in the PHC80-1, PHC80-3, and PC80-1-A reports. All State files have been released. Data from the STF 1A file are also available on microfiche.

STF 2 contains 2,292 cells of detailed complete-count population and housing data, of which 962 are repeated for race and/or Spanish origin groups present in the tabulation area. Data are summarized for the United States, regions, divisions, States, SCSA's, urbanized areas, counties, county subdivisions, places of 1,000 or more inhabitants, census tracts, American Indian reservations, and Alaska Native villages. This file set includes data shown in the PHC80-2, PC80-1-B, and HC80-1-A reports. Individual State files are being released as of February 1982.

STF 4 is the geographic counterpart of STF 2, but the number of cells of data is approximately three times greater. STF 4 provides detailed population and housing data estimated from the sample, some of which are repeated for race, Spanish origin, and ancestry groups. Data are summarized for areas similar to those shown for STF 2, except that data for places are limited to those with 2,500 or more inhabitants. This file set includes data shown in the PHC80-2, PC80-1-C, and HC80-1-8 reports. STF 4 is tentatively scheduled to be available from mid to late 1982.

STF 5 contains over 100,000 cells of population and housing data estimated from the sample and provides highly detailed tabulations and cross-classifications for States, SMSA's, and counties and cities of 50,000 or more inhabitants. Most subjects are classified by race and Spanish origin. This file set includes data shown in the PC80-1-D and HCeSO-2 reports. STF 5 is tentatively scheduled to be available from mid to late 1983.

Census of Population and Housing, 1980-Master Area Reference File (MARF)

The file, organized by State, provides counts for total population, and provisional counts for five racial categories and Spanish/Hispanic origin. Summaries are provided for the State, counties, minor civil divisions (MCD's) or census county divisions (CCD's), incorporated places or place segments witnin MCL)'s/CCD's, remainders of MCD's/CCD's, election precincts in certain States or portions of certain States, census tracts or block numbering areas, block: groups and blocks or, for areas that are not block numbered, enumeration districts (ED's). The figures presented in P.L. 94-171 may differ from those shown in STF 1. The changes reflect corrections of errors found after P.L. 94-171 was prepared. Microfiche (and paper photo copy of microfiche) of tne P.L. 94-171 Population Counts file is also available.

U.S. Bureau of the Census. "Census of Population and Housing, 1980: Summary Tape File 3 Technical Documentation" (this document). The documentation includes this abstract as well as additional information about the file and a data dictionary. One copy accompanies each file order. When ordered separately, it is available for $5.00 from Data User Services Division, Customer Services (Tapes), Bureau of the Census, Washington, D.C. 20233.

This map series provides coverage of densely settled areas of selected counties and county equivalents. These maps are referred to as the Metropolitan Map Series (MMS) when the maps cover SMSA areas and as the Vicinity Map Series (VMS) when the maps cover areas not in an SMSA. For a more detailed discussion of the MMS/VMS, see the section, "1980 Census Maps."

The maps cover all counties and county equivalents except where the Metropolitan Map Series/Vicinity Map Series (MMS/VMS) sheets cover an entire county. Most county maps are based on maps supplied by State transportation or highway departments on which the Bureau has superimposed boundaries and identifiers for most areas for which data are tabulated. There are inserts to county maps for some counties that contain American Indian reservations. For a more detailed discussion on county maps and American Indian reservation maps, see the section, "1980 Census Maps."

Place maps are used for places not shown on MMS/VMS and show map features within the corporate limits of a municipality or within boundaries established for a census designated place (CDP). If census boundaries and identifiers for an area adjacent to a place are shown, the map is referred to as a place-and-vicinity map. For a more detailed discussion on place maps, see the section, "1980 Census Maps."

This publication is a comprehensive guide to 1980 census data. It covers 1980 census subject content, procedures, geography, statistical products, limitations of the data, sources of user assistance, notes on data use, a glossary of terms, and guides for locating data in reports and tape files. The guide is issued in loose-leaf form and sold in parts (Rl-A, -B, etc.) as they are prepared. Part A, Text is currently available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. S/N 003-024-03625-8. Price is $5.50.

The index features the respondent's industry (employer's kind of business) and occupation (employee's kind of work) as in the 1980 Census of Population, Current Population Survey, and other demographic surveys conducted by the Bureau of the Census. The index lists approximately 20,000 industry and 29,000 occupation titles in alphabetical order. It is a comprehensive list of specific industries and occupations developed over time and continuously updated through review of census and survey questionnaires. It is available from the Superintendentof Documents, U.S. Government Printing Office, Washington, D.C. 20402. S/N 003-024-02574-4. Price is $9.50.

The index presents, for each category in the industrial and occupational classification system, the individual titles that constitute each of the 231 industry and 503 occupation categories in the classification systems. The individual titles are the same as those shown in the Alphabetical Index. The 1980 occupation classification reflects the new U.S. Standard Occupational Classification (SOC). As in the past, the 1980 industry classification reflects the Standard Industrial Classification (SIC). It is available from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. S/N 003-024-02575-2. Price is $7.00.

New Census Bureau products released each month are listed in the MPA. These products include publications, technical documentation, data files, published maps, and microfiche. To be added to the mailing list, contact Data User Services Division, Customer Services (Publications), Bureau of the Census, Washington, D.C. 20233.

Related Printed Reports And Microfiche:
Listed below are some of the products which are currently available or will be released. For a complete listing, see the 1980 Census Users' Guide. The products may be ordered from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 unless otherwise indicated.

Data are derived from STF 2 and include statistics on household relationship, age, sex, marital status, race and Spanish origin for the following areas or their equivalents: States, standard consolidated statistical areas (SCSA's), standard metropolitan statistical areas (SMSA's), urbanized areas , counties (by rural residence), county subdivisions, places (and towns and townships in selected States) of 1,000 or more inhabitants, American Indian reservations, and Alaska Native villages. These reports are issued separately for the United States, each State, the District of Columbia, Puerto Rico, Guam, Virgin Islands, American Samoa, the Trust Territory of the Pacific Islands, and the Northern Mariana Islands.

In addition to selected subjects which are shown in the PC80-1-B reports, statistics are presented on nativity, State or country of birth, citizenship and year of immigration for the foreign- born population, language usage and ability to speak English, ancestry, fertility, family composition, type of group quarters, residence in 1975, journey to work, school enrollment, years of school completed, disability, veteran status, labor force status, occupation, industry, class of worker, labor force status in 1979, income in 1979, and poverty status in 1979. Each subject is shown for some or all of the following areas or their equivalents: States, counties (by rural and rural farm residence), places (and towns and townships in selected States) of 2,500 or more inhabitants, SCSA's, SMSA's, urbanized areas, American Indian reservations, and Alaska Native villages.

Statistics on population characteristics are presented in considerable detail and cross-classified of age, race, Spanish origin, and other characteristics. Each subject is shown for the State or equivalent area, and some subjects are also shown for rural residence at the State level. Most subjects are shown for SCSA's of 250,000 or more inhabitants, and a few are shown for central cities of these SMSA's.

Statistics on units at address, tenure, condominium status, number of rooms, persons per room, plumbing facilities, value, contract rent, and vacancy status are shown for some or all of the following areas or their equivalents: States, counties, county subdivisions, places (and towns and townships in selected States) of 1,000 or more inhabitants, SCSA's, SMSA's, urbanized areas, American Indian reservations, and Alaska Native villages. Selected tables contain housing characteristics for urban and rural areas.

Some subjects included in the HC80-1-A reports are also shown in this report. Additional subjects include units in structure, year householder moved into unit, year structure built, heating equipment, fuels, air conditioning, water and sewage, gross rent and selected monthly ownership costs. The statistics are shown for some or all of the following areas or their equivalents: States (by urban, rural-nonfarm, and rural-farm residence), counties, places (and towns and townships in selected States) of 2,500 or more inhabitants, SCSA's, SMSA's, urbanized areas, American Indian reservations and Alaska Native villages.

This volume presents statistics in considerable detail and cross- classification for most of the 1980 census housing subjects. Most statistics are presented by race and Spanish origin for areas with at least a specified number of the relevant population groups. Data are shown for States or equivalent areas, SMSA's and their central cities, and other cities of 50,000 or more inhabitants. There is one title for each SMSA, and one title for each State, the District of Columbia, and Puerto Rico. The U.S. Summary shows these statistics for the United States and regions.

Data provided are derived from STF 1 and include final population and housing counts (totals) and statistics on selected characteristics based on responses to complete-count (100-percent) questions. Data are shown for individual blocks in the blocked portion of each standard metropolitan statistical area (SMSA), places of 10,000 or more inhabitants outside of SMSA's, and for areas which contracted with the Census Bureau to provide block statistics. There is one title for each SMSA with block-numbered areas within the SMSA, and one title for each State with block-numbered areas outside of SMSA's. Block reports and maps on paper stock are available from the U.S. Government Printing Office, Washington, D.C. 20402. Microfiche paper prints of the reports are available from Data User Services Division, Customer Services (Microfiche), Bureau of the Census, Washington, D.C. 20233.

Data for selected population and nousing subjects derived from STF 2 and STF 4 are shown by census tracts for standard metropolitan statistical areas (SMSA's), central cities, component SMSA counties, selected nonSMSA counties, and places of 10,000 or more inhabitants within SMSA's and selected counties. Some tables are based on 100-percent or complete-count tabulations while others are based on sample tabulations. There is one report for each SMSA and one for the tracted balance of each State. Tract comparability tables are included in this publication. Maps are also provided with the tract reports.

This publication series is derived from STF 1 and STF 3 and shows selected population and housing statistics based on complete count and sample estimate data for States, SMSA's, counties, functioning minor civil divisions (20 specified States), and incorporated places. There is one report for each State, the District of Columbia, and Puerto Rico.

STF 3A is arranged so that tapes for individual States or State equivalents can be purchased separately. Tapes are available at 1600 bpi or 6250 bpi, 9-track, at a cost of $140 per reel. If data for more than one State are stacked on a single reel at a customers request, the cost is $165 per reel. For information on the number of reels and release date for each State, subscribe to the Monthly Product Announcement (MPA). The MPA is available without charge and may be ordered using the Customer Services order form for publications.

STF 3B was originally part of the Census Bureau's 1980 program, but budget cutbacks forced cancellation of these plans. Since this cancellation, the Bureau signed a contract with National Planning Data Corporation (NPDC) of Ithaca, New York to prepare STF 3B as a special tabulation. During the first 18 months following the release of each State file, users may discuss purchasing the file from NPDC. After eighteen months, the Bureau will sell the file as a standard public use computer tape.

STF 3C is a national file which will be issued as a single file when STF 3A is completed.

STF 3 can be ordered using the Customer Services order form for tapes. When ordering from the Bureau, please refer to file number Cu SUM 80 010A for STF 3A, Cu SUM 80 010B for STF 3B, and Cu SUM 80 010C for STF 3C. Please indicate tne name of the State(s) when ordering STF 3A and STF 3B.

STF 3A will also be available on microfiche. Information on availability and number of fiche per State will be provided in the MPA or can be obtained from Customer Services Branch (301) 763-4100.

STF 3A and STF 3B each comprise one file per State. STF 3C will be a single file for the Nation. Each file has a logical record length of 12,096 characters with six record segments of 2,016 characters each. The block size for the files varies with user specifications. A printout listing the block size and block count will be sent with each file.

This abstract provides general information about the geographic coverage of STF 3. For detailed information about hierarchy and splits across higher levels of geography, see the section "File Structure and Geographic Coverage."

File A of STF 3 provides summaries for the State or State equivalent, counties or county equivalents, minor civil divisions (MCD's) or census county divisions (CCD's), places or place segments within MCD's/CCD's and remainders of MCD's/CCD's, census tracts or block numbering areas (BNA's), and block groups (BG's) or, for areas that are not block-numbered, enumeration districts (ED's). These summaries are provided in hierarchical sequence. Summaries are also presented on File A for places and congressional districts. (1980 congressional district data presented in STF 3 is for districts delineated for the 96th Congress.)

File B provides summaries for each 5-digit ZIP code area within a State, and for 5-digit ZIP code areas within a State within standard metropolitan statistical areas (SMSA's) or portions of SMSA's within a State, within county, county portion, or county equivalent.

File C is also referred to as the National file. It has summaries for the following levels: United States, census regions, census divisions, States, standard consolidated statistical areas (SCSA's), standard metropolitan statistical areas (SMSA's), and urbanized areas (UA's). SCSA's, SMSA's, and UA's which cross State lines also have a record for the SCSA, SMSA, or UA portion within each State. Summaries are included for counties, places of 10,000 or more population, MCD's of 10,000 or more population in eleven selected States, and congressional districts.

This file primarily contains sample data inflated to represent the total population. In addition, the file contains 100-percent counts and unweighted sample counts of persons and housing units. STF 3A, STF 3B, and STF 3C have identical tables and format except for the omission of 100-percent counts for population and housing in STF 3B. Population and housing items tabulated include the following:

Summary Tape File 3 (STF 3) is one of a series of summary data files available from the 1980 census. The file corresponds to the 1970 Fifth Count file and is composed of three parts - STF 3A, STF 3B, and STF 3C. File STF 3A is tentatively scheduled for release on a State-by-State basis in mid 1982. STF 3B will be released on a State-by-State basis first to National Planning Data Corporation (NPDC) which is funding the special tabulation. The file will be sold by NPDC for 18 months after which the file will be sold by the Census Bureau as a standard public use tape. STF 3C will be issued after all STF 3A and STF 3B files have been released.

For each geographic area there will be a 12,096-character census logical record. Because of its large record size, STF 3 is divided into six segments of 2,016 characters each with each. These segments are identified within the geographic identification section repeated for each segment.

The first segment of each census logical record begins with 252 characters of geographic information and the suppression flags, while each subsequent segment begins with 102 characters of geographic information.

The record segments were arranged so that individual tables do not cross segment boundaries. Because of this, most segments have some padding at the end. The following chart illustrates the segmentation on STF 3. For a concise description of the geographic coverage of each file in STF 3, see Appendix A.

This file contains summary level data which follow a geographic hierarchy. In File A, block groups (BG's) or enumeration districts (ED's) are nested within a tract, block numbering area (BNA), or tract/BNA segment which in turn is sequenced within a place, place segment, remainder of MCD or remainder of CCD, then within a minor civil division (MCD) or census county division (CCD), and within a county or county equivalent. Data summaries are presented at each level. When a level of geography is split across the next higher level, only the portion within the higher level will be shown on the summary. For example, if tract 0001 is split between place 0005 and 0010, the summary for the portion in place 0005 will appear in the hierarchy with the place 0005 summaries while the portion in place 0010 will appear with the place 0010 summaries.

In addition, place and congressional district summaries are presented separately from the hierarchically organized summaries. Each summary is identified by a summary level code in positions 10-11 of the record as well as at the beginning of each segment. Figure 1 outlines the specific geographic hierarchy in STF 3A. Each indentation indicates the next lower level of the geographic hierarchy. Following Figure 1 is a discussion of each summary level in the hierarchy.

Figure 1. Geographic Hierarchy of STF 3A

The State record (Summary Level 04) contains a summary for the State or State equivalent.

This file contains summary level data which follow the geographic hierarchy indicated la figure 1 below. Records are shown for the State, a congressional district, then all counties within the congressional district. All county records are followed by records for all places of 10,000 or more within the congressional district and then by minor civil divisions (MCD's) with a population of 10,000 or more, in 11 selected States, within the congressional district. When a county, place, or MCD is split between two or more congressional districts, the summary record for a county, place, or MCD contained within each of the congressional districts geographic hierarchy will show only the data for that portion contained within the congressional district.

Figure 1 below outlines the geographic hierarchy. Following Figure 1 is a discussion of each summary level in the hierarchy.

Figure 1. Geographic Hierarchy of STF 3D

The State record (Summary Level 04) contains a summary for the State or State equivalent.

The Congressional District record (Summary Level 33) contains a summary for each congressional district within the State according to the congressional district boundaries established for the 98th Congress.

The County record (Summary Level 37) contains a record for each county or county equivalent, including independent cities, or portion of a county, county equivalent, or independent city located within each congressional district.

The Place record (Summary Level 38) contains a summary for each place with 10,000 or more inhabitants, as published in the 1980 census, or portion of a place, located within the congressional district.

The MCD record (Summary Level 39) contains a summary for each county subdivision (minor civil division) with 10,000 or more inhabitants, as published in the 1980 census, or portion of such an MOD, located within the congressional district for 11 selected States.

The county record (Summary Level 11) contains a summary for each county or county equivalent, including independent cities, within the State in FIPS code sequence.

The minor civil division (MCD)/census county division (CCD) record (Summary Level 12) contains a summary for each MCD/CCD within the county in census code sequence.

The place or remainder of MCD/CCD record (Summary Level 13) provides a summary for each place within an MCD/CCD in place code sequence. These may be places or, when places cross MCD/CCD boundaries, portions of places. A remainder of MCD/CCD record will be generated only if there is a place in the MCD/CCD. This record will cover all areas outside of places and will have a pseudo place code of 9999.

The combination of census tract/block numbering area (BNA) or untracted remainder of MCD/CCD (Summary Level 14), and block group (BG) (Summary Level 15) or enumeration district (ED) (Summary Level 16) summaries will vary according to the situation. The four situations are as follows:

Census tract or block numbering area (BNA)/block group (BG) - When a census tract or BNA is entirely block numbered, a summary is shown for each tract/BNA or tract/BNA portion within MCD/CCD and place; place segment, or remainder of MCD/CCD, and for each block group or block group segment within tract/BNA or tract/BNA portion.

Census tract/ED1 - When the area is tracted but contains no blocks, a summary is shown for each tract or tract portion within MCD/CCD and place, place segment, or remainder of MCD/CCD, and for each ED within tract.

Not Tracted/ED - When an area is not tracted or not within a BNA, a summary is shown for each ED within the MCD and place, place segment, or remainder of MCD/CCD. A pseudo-tract code of 999999 will appear in the tract code field.

Census tract/BG-ED1 - When a tract is partially block numbered, there will be a mixture of BG and ED summaries for the tract or the tract portion within MCD/CCD and place, place segment, or remainder of MCD/CCD. BG summaries will precede those for ED's in this situation.

The place total record (Summary Level 27) provides a summary for each place within the State. The place records are arranged by census place code.

The congressional district summary (Summary Level 33) contains summaries for each congressional district within the State arranged in numeric sequence. These are the congressional districts designated for the 96th Congress.

1When a tract, block numbering area, or block group crosses a place, MCD, or CCD boundary, there will be separate summaries for each portion within the higher-level entities. No totals for split tracts, BNA's, or block groups are provided.

As with STF 3A, each logical record summary of STF 33 is identified by a summary level code in positions 10-11 of the first segment as well as at the beginning of each segment. When the level of geography is split across the next higher level, only the portion within the higher level of geography will be shown, (See example on STF 3A description above.) The geographic hierarchy for STF 3B appears in Figure 2.

STF 3B has records for each 5-digit ZIP code within a State in numeric order (Summary Level 35) followed by records for 5-digit ZIP codes within a State arranged in numeric order by SMSA or portion of SMSA, then county or county equivalent or \portion of county or county equivalent (Summary Level 36).

This file is essentially a national file which will be issued only after STF's 3A and 38 have been released for all States. The geographic hierarchy for this file is shown in Figure 3 below.

The United States summary (Summary Level 01) provides a summary for the United States. (50 States and the District of Columbia).

The region summary (Summary Level 02) has a summary for each of the four census regions in the United States.

The division summary (Summary Level 03) has a summary for each of the nine census divisions in the United States.

The State summary (Summary Level 04) has a summary for each State or State equivalent in ascending FIPS State code sequence.

The standard consolidated statistical area (SCSA) summary (Summary Level 05) has a summary for each SCSA in the United States in ascending SCSA code sequence.

The SCSA/State summary (Summary Level 06) is a summary for the portion of the SCSA in each State in which a multi-State SCSA is located. These are arranged in ascending FIPS State code within SCSA code sequence.

The standard metropolitan statistical area (SMSA) summary (Summary Level 07) provides a summary for each SMSA in the United States in ascending SMSA code sequence.

The SMSA/State summary (Summary Level 08) provides a summarv for the portion of the SMSA in each State in which a multi-State SMSA is located. These summaries are arranged in ascending FIPS State code within SMSA code sequence.

The urbanized area (UA) summary (Summary Level 09) contains a summary for each UA in the United States in ascending UA code sequence.

The UA/State summary (Summary Level 10) provides data for the portion of the UA in each State in which the multi-State UA is located. These are in ascending FIPS State code within UA code sequence.

The State/county summary (Summary Level 11) provides a summary for each county or county equivalent, including independent cities, in the United States. These are arranged by FIPS county code within FIPS State code.

The State/place summary (Summary Level 27) provides a summary for all places of 10,000 or more population within the United States. These are arranged by census place code within FIPS State code.

The State/MCD summary (Summary Level 28) provides a summary for MCD's of 10,000 or more population within 11 States. The sequence is by MCD sequence number within FIPS State code. The 4-digit MCD number differs from the 3-digit MCD code by identifying MCD's in alphabetic order within State. The 11 States are as followsConnecticut, Maine, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Wisconsin.

The congressional district summary (Summary level 33) contains a summary for each congressional district in the United States in congressional district number sequence within FIPS State code.

Calculation of median values is done using a continuous distribution with the whole number as the mid-point of the class interval. However, if the median falls within the upper or lower interval, it is set to a specified value. Listed below in Figure 4 are the upper and lower intervals for each median in STF 3 and the median value set when it falls within that interval.

Figure 4. Upper and Lower Intervals for Computation of Median

I. Median Household And Family Income

Value

Description

Less than $2,500

Median household and family income is less than S2,500. Median is set at $2,499.

$75.000 or more

Median household and family income is greater than $75.000. Median is set at $75,001.

II. Median Income (Unrelated Individuals)

Value

Description

Less than $1,000

Median income is less than $1,000. Median is set at $999.

$50,000 or more

Median income is $50.000 or more. Median is set at $50,001.

III. Median Gross Rent

Value

Description

Less than $60

Median gross rent is less than $60. Median is set at $59.

$500 or more

Median gross rent is $500 or more. Median is set at $501.

IV. Median Selected Monthly Owner Costs (With a mortgage)

Value

Description

Less than $100

Median selected monthly costs for mortgage holders are less than $100. Median is set at $99.

$750 or more

Median selected monthly costs for mortgage holders are $750 or more. Median is set at $751.

V. Median Selected Monthly Owner Costs (No Mortgage)

Value

Description

Less than $50

Median selected monthly owner costs (no mortgage) are less than $50. Median is set at $49.

$250 or more

Median selected monthly costs for mortgage holders are $250 or more. Median is set at $251.

To maintain the confidentiality promised respondents and required by law, the Census Bureau takes precautions to make sure that its public data, in print or on tape, do not disclose information about particular individuals or housing units; therefore, the Bureau suppresses tabulations of characteristics for very small groups of people or housing units. On summary tapes, zeroes are entered in suppressed cells. Flag fields which indicate suppression are shown on each record. However, a zero in a cell does not automatically mean suppression. Only by checking the suppression flag can it be determined if the zero in a specific table is suppressed data or an actual count of zero.

This discussion outlines the rules for suppression of sample data, how its occurrence can be identified by the user, and how to handle it.

Characteristics of persons other than race or Spanish origin (e.g., age, relationship) are shown only if there are 30 or more persons in the geographic area. For example, on a record for a census tract with a population of 1 to 29 persons, population characteristics such as age and relationship are suppressed. Only counts for total population and the number of persons within specific race or Spanish origin groups are provided.

However, when the geographic area being summarized has 30 or more persons, no suppression of population characteristics will occur except possibly when tables are further cross-classified by race or Spanish origin. The rules for this type of suppression are outlined below in Suppression of Tables Cross-Classified by Race or Spanish Origin.

Characteristics of year round housing units which are not classified by occupancy status (e.g., number of rooms, plumbing facilities, etc.) are suppressed only when there are fewer than ten year-round housing units in the geographic area being tabulated regardless of the number of occupied housing units or the number of persons.

Population and housing characteristics cross-classified by race or Spanish origin are subject to an additional level of scrutiny. This level requires the 30 person or ten household criteria stated above of applied to each race or Spanish origin group.

Individual cells of data for specific race or Spanish origin groups are not suppressed when there are 30 or more persons of that group in a geographic area unless required by complementary suppression.

The population and housing suppression criteria are applied independently of one another. For example, if there are 32 White persons but only eight households with white householders, the person characteristics will be shown, but the family, household, and housing characteristics will be suppressed.

In some cases complementary suppression is applied to prevent the derivation of suppressed data by subtraction. For instance, when a table shows the number of persons in unit for all households and also for renters, there must be at least ten owners and ten renters for the renter data to be shown; otherwise, the characteristics of the owners could be derived by subtracting renter data from data for all households.

Suppressed data cells contain zeroes. To distinguish between zeroes as suppression and zeroes as valid data, occurrences of suppression are identified by a series of flag fields in the geographic identification portion of each logical record. Programmers developing software should include procedures to check these fields for the presence of suppression and, if necessary, to flag the output of any cumulation which includes one or more suppressed fields.

In reviewing the data dictionary, the programmer can determine which suppression flags indicate suppression for particular tables by checking either the table description or the flag description. An example of each follows.

Example: The boxed illustration on the following page is the table description as it appears in the data dictionary. The next portion illustrates the suppression flag to which the table description refers.

Figure 7 below, lists each suppression flag, its location within the record, and the tables or cells within tables which are affected when suppression is applied. The suppression flag field which applies to each table or portion of a table is also identified in the table description in the data dictionary. The flags are located in the geographic identification section of each record in positions 205236.

In most cases, suppressed data values are small (fewer than 10 or 30) except where a large population is affected by complementary suppression. Therefore, in certain noncritical applications, users may simplify programming operations by ignoring suppression and treating suppressed cells as zero cells. However, when geographic entities are being summed to higher levels or new geographic areas are being created, suppression will usually result in a downward bias in the totals.

The data dictionary contains complete information regarding geographic codes, table information, and a detailed table layout. The following is an outline of information provided in both the geographic and table identification portions of the file.

The first line of each geographic identification variable gives the name, size/scale, begin position, relative begin position, and the variable label. Following those items, on subsequent lines, are any applicable notes and value codes. Each of these items is defined below.

Following the Data Type is a description of the data item. This heading is not labeled on the data dictionary. This section also provides any relevant notes or footnote references. In addition, any value codes necessary for the data item are listed and labeled here.

The documentation of tables begins, with the name, size/scale, begin position, relative begin position for the table, data type, and the number of cells. This information is followed by the table title, applicable suppression flags, universe definition, applicable footnotes, stratifier identification, and a listing of the cells.
These items are defined below.

The title of the table identifies the stratifiers used in the table, and the number of categories in each stratifier. For example, this title indicates that there are five categories of race and four categories of school enrollment identified in the table.

This section lists the stratifiers used in the table, in the order in which they appear on the data tape. For example, this table begins with the first category of race cross classified by the four school enrollment categories. This is followed by the four remaining categories of race, each of which is cross classified by the four categories of school enrollment. Headers representing stratifiers are followed by a colon and are not counted as cells.

CENSPAC users who want a data dictionary report listing the beginning position of all cells may use the CENSPAC Documentor program with the "long" option and the machine-readable data dictionary for STF 3 to obtain such a listing.